Commercial and industrial notification systems require the installation and use of notification devices. These devices can include, but are not limited to, speaker amplifiers, tone generators, voice output generators, and optical signaling devices such as strobe lights. Such notification devices may be used for general signaling and emergency evacuation. For example, a system of audible and visible alarm devices, including sirens and strobe lights, may be furnished as part of a fire alarm system for an office building.
In industrial applications, these devices must often be located in areas exposed to the elements, such as exterior building walls lacking substantial overhead protection. For example, it may be necessary or desirable to furnish notification devices in exterior locations of a chemical plant. Notification devices installed outdoors will be subject to environmental conditions, including precipitation. Therefore, it is possible that water will intrude into the notification device, potentially interfering with its operation or damaging its components.
Underwriters Laboratories (UL) requires that any devices suitable and listed for outdoor use must have the ability to operate when exposed to such conditions. This ability is confirmed by performing a simulated rain test for a pre-established period of time during which the device must operate without failure. The unit must not only operate, but also prevent water from entering the operating electrical compartment.
Accordingly, it is desirable to provide a notification device that inhibits the intrusion of rain into the operating electrical compartment of the device while permitting the free passage of sound from the device into surrounding environs.